I guess it depends on the human!
If the human has a viral disease then obviously it can be passed to a person with a bite and is more serious.
I am assuming you are questioning more on bacterial issues..and it is true that the bacteria in a cats mouth cause more of an infection than a human. Cats teeth are so fine they are able to puncture deeper into the tissue and because of them not being avid teeth brushers and cats...the types of bacteria...planted deep in the tissue can cause people significant problems.
Hope this helps!
Dr.V
Dr. D.A. Vamvakias
Veterinarian